What specific pages are you asking about? There are several for LDDA, such as barcode web forms, ERP report pages, IP to Location, etc.
All or any of them actually.
ERP Reports can use a different file as long as it's in C:\inetpub\wwwroot\LANDesk\LDMS\report. When you create the report you can specify the image.
Barcode web forms can have a different image specified by replacing the header.png in C:\inetpub\wwwroot\LANDesk\LDMS\MP_CD
The Map IP Gateways to Locations page can have a different specified by replacing the AddrHeader.png under C:\inetpub\wwwroot\LANDesk\LDMS\MP_SLM
Mind you, replacing the default images isn't an officially supported branding option. While there isn't an obvious reason why it wouldn't work, there isn't any documentation on image size, supported formats, etc. I haven't personally done much testing on this, so I can't guarantee anything.
As for editing the layout, you would have to edit the actual .aspx pages, which isn't a good idea. You can drop an ER here for a page editor, and if this is something enough people want, product management will evaluate it.
Thank you, I will play around with it and see what I end up with.